From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Conclusions on two types of high power cylinder heads for 4-cylinder and 6-cylinder engines.
| Identifier | ExFiles\Box 132\4\ scan0255 | |
| Date | 9th September 1940 | |
| 1124 COPY. Jnr.{Charles L. Jenner} from Rm.{William Robotham - Chief Engineer} C. to Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} HIGH POWER CYLINDER HEADS. ------------------------- The conclusion I have come to with regard to the two types of cylinder head which we tried is the small advantage in detonation which we gained from this new type head did not justify the possible increase in roughness, particularly since the flush top piston with the old type head enabled us to use a c/r of about 6.6 on pool petrol. Unless, therefore, the new type head is a big advantage for spark plug location on the 4-cylinder engine, we believe we should not use it. We know that the new type head was necessary in order to get a high c/r on the small bore, 6-cylinder engines, without having a completely new cylinder head pattern. Rm.{William Robotham - Chief Engineer} | ||